It is known to provide a sheet metal container, e.g. a drum, with one or both of its end closures formed as cup-shaped members whose outer dimensions correspond to the inner dimensions of open ends of a generally cylindrical sheet metal body into which the end closures is inserted.
The outer edge of the end closure can rest upon the end face of the generally cylindrical body and can have an inwardly rolled portion placed against the outer surface of the body. As described in German Patent Document DE-GM 8711650 (see U.S. Pat. No. 4,905,858), relatively cylindrical parts of an end closure and the body are secured together by a transverse weld between them.
This system has an advantage over more complicated techniques for securing an end closure to the sheet metal body and which required corresponding margins of the body and the end closure to be rolled together and systems in which a sealing mass between the end closure and the generally cylindrical body, and which had to be compatible with the contents of the drum, were required.
These earlier systems had the drawback that reuse of the barrel required cleaning which was often inhibited by the presence of joints formed by rolling two parts together. The sealing mass often also interfered with the ability to remove the end closure and thereby recondition the drum.
With the system of the aforementioned German Patent Document and U.S. Patent, these drawbacks could be avoided in that the sealing mass could be eliminated entirely and it was not necessary to fold together margins of the end closure and the sheet metal body.
However, even this system has been found to have certain drawbacks. For example, it was found to be necessary, especially where the end closure and the cylindrical body had to be welded together, to fabricate the assembly with very narrow manufacture tolerances so that place between the end closure and the body was excluded and the end closure could be fitted tightly within the body. Such narrow manufacturing tolerances, of course, required special fabrication techniques which were expensive.
A snug fit with narrow manufacturing tolerances often required that the end closure be pressed into the body with forces which tended to give rise to deformation of the parts which were assembled. This could result in defects in the fabrication of the drum.
Still another disadvantage of the earlier system was the fact that the location of the weld seam at the location intermediate the height of the end closure, between the floor of the cup-shaped structure and the outwardly bent flange thereof which had its extremity rolled inwardly against the body, i.e. in intermediate locations along the cylindrical wall of the cup shaped structure, could result in a gap, crevice or the like between the body and the end closure in which a portion of contents of the drum could remain to interfere with reuse, cleaning and reconditioning, or which could constitute a location at which corrosion could occur.